BQE BillQuick Web Suite SQL Injection Remote Code Execution Vulnerability (CVE-2021-42258) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTBQE BillQuick Web Suite 2018 through 2021 before version 22.0.9.1
Unauthenticated remote attackers can execute arbitrary OS commands with MSSQLSERVER$ privileges via SQL injection and xp_cmdshell activation, potentially deploying ransomware
Immediately upgrade BillQuick Web Suite to version 22.0.9.1 or higher, disable xp_cmdshell on the database, and apply WAF rules
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Immediately upgrade your BQE BillQuick Web Suite installation to version 22.0.9.1 or later.
2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, disable the 'xp_cmdshell' feature in your MSSQL database to prevent remote code execution.
Execute the following SQL script to disable 'xp_cmdshell':
-- Disable xp_cmdshell to mitigate RCE risk
USE master;
GO
EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
GO
EXEC sp_configure 'xp_cmdshell', 0;
RECONFIGURE;
GO
EXEC sp_configure 'show advanced options', 0;
RECONFIGURE;
GO3. Log Audit & IoC Verification Commands
Audit IIS access logs and SQL Server logs for suspicious patterns in the 'txtID' parameter, such as single quotes, semicolons, or database administration commands.
Use the following PowerShell script to search IIS logs for potential SQL injection attempts:
# Search IIS logs for suspicious SQL injection patterns targeting txtID
$LogPath = 'C:\inetpub\logs\LogFiles\W3SVC1\*'
Get-ChildItem -Path $LogPath -Filter *.log |
Select-String -Pattern 'txtID' |
Select-String -Pattern 'xp_cmdshell|exec|sp_configure|union|select' |
Out-File -FilePath 'C: emp\detected_ioc_attempts.txt'Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-42258) is a critical SQL injection (CWE-89) vulnerability in BQE BillQuick Web Suite due to insufficient input validation and lack of parameterized queries on the login interface. An unauthenticated remote attacker can inject malicious SQL commands through parameters such as 'txtID' (the username field) to manipulate backend database queries.
2. Exploitation Mechanics & Attack Scenario
An attacker sends a crafted HTTP POST request containing SQL injection payloads in the 'txtID' parameter. If the web application connects to the Microsoft SQL Server (MSSQL) database with elevated privileges (such as 'sa'), the attacker can leverage this access to enable the 'xp_cmdshell' extended stored procedure. This allows the execution of arbitrary operating system commands under the security context of the database service account (MSSQLSERVER$), enabling the download and execution of ransomware payloads.
3. Infrastructure & Business Impact
This vulnerability has been actively exploited in the wild to deploy ransomware and is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. With an EPSS score exceeding 0.75, the likelihood of exploitation is extremely high. Successful exploitation leads to complete compromise of the host system, unauthorized access to sensitive billing data, and potential business-wide ransomware disruption.
Official Vendor Advisories & References
BQE BillQuick Web Suite 2018 through 2021 before 22.0.9.1 allows SQL injection for unauthenticated remote code execution, as exploited in the wild in October 2021 for ransomware installation. SQL injection can, for example, use the txtID (aka username) parameter. Successful exploitation can include the ability to execute arbitrary code as MSSQLSERVER$ via xp_cmdshell.
Frequently Asked SecOps Questions (CVE-2021-42258)
FAQQ1. How critical is CVE-2021-42258 and is it actively exploited in the wild?
CVE-2021-42258 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 75.2%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-42258?
Primary impacted vendors include bqe across billquick_web_suite. Scope summary: BQE BillQuick Web Suite 2018, 2019, 2020, and 2021 (all versions prior to 22.0.9.1)
Q3. What temporary mitigations or workarounds exist for CVE-2021-42258 before patching?
[Mitigation] Immediately upgrade BillQuick Web Suite to version 22.0.9.1 or higher, disable xp_cmdshell on the database, and apply WAF rules Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-42258
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